from flask import Flask
from flask_login import LoginManager
from . import db

def create_app():
    app = Flask(__name__)

    app.config['SECRET_KEY'] = 'secret-key-goes-here'

    # authorization-related routes 
    from .auth import auth as auth_blueprint
    # main routes
    from .main import main as main_blueprint

    app.register_blueprint(main_blueprint)
    app.register_blueprint(auth_blueprint)

    login_manager = LoginManager()
    login_manager.login_view = 'auth.login'
    login_manager.init_app(app)

    @login_manager.user_loader
    def load_user(user_id):
        # must return None in case no such user exists
        return db.get_user(user_id) 

    db.startup() 

    return app